With a conventional projector of a laser-scanning type, there is a situation where the laser optical device illustrated in FIG. 13 is used to compensate for a brightness on a screen being deficient. The conventional laser optical device illustrated in FIG. 13 is provided with semiconductor laser elements 101 and 102, a polarizing prism 103, and a collimating lens 104.
The semiconductor laser elements 101 and 102 emit laser lights of identical wavelengths. However, the semiconductor laser element 101 is a laser element that outputs a p-polarized light, and the semiconductor laser element 102 is a laser element that outputs an s-polarized light.
The polarizing prism 103 has a polarizing surface 103A that transmits a p-polarized light and reflects an s-polarized light. By the laser light emitted from the semiconductor laser element 101 (p-polarized light) being transmitted through the polarizing surface 103A and the laser light emitted from the semiconductor laser element 102 (s-polarized light) being reflected at the polarizing surface 103A, both laser lights become incident to the collimating lens 104 as one laser light.
The collimating lens 104 converts the incident light into a parallel light. The parallel light emitted from the collimating lens 104 is reflected by a biaxial MEMS (microelectromechanical system) mirror 105 provided to the conventional projector of the laser-scanning type and is projected on a screen 106. The laser light projected on the screen 106 is scanned according to biaxial driving of the biaxial MEMS mirror 105.
By using the conventional laser optical device illustrated in FIG. 13, a brightness on the screen 106 can be substantially doubled from that of a situation where a laser optical device having only one laser element is used.